Why Is the ΔG of ATP Hydrolysis in the Cell

Multiple Choice

Why is the ΔG of ATP hydrolysis in the cell about twice as great as the ΔG of ATP hydrolysis in a test tube under standard conditions?

A) A cell is an open system, whereas a test tube is a closed system.
B) ATP hydrolysis in a test tube releases more heat than ATP hydrolysis associated with cellular metabolism.
C) Reactant and product concentrations in the test tube are different from those in the cell.
D) ATP hydrolysis in cells is catalysed by enzymes, whereas the reaction in a test tube occurs spontaneously.